1. Field of the Invention
The present invention relates to a history recording apparatus which is incorporated in an electronic apparatus so as to record the operation history data referred to during maintenance.
2. Description of the Related Art
In many large-scale retail shops, labels indicating the article information, such as article codes, names, prices, and the dates of manufacture or production, are attached to the commodities on sale. Labels of this kind are prepared by means of a label printer. The label printer prints article information supplied from a host computer on a roll of label paper and feeds the printed portions of the label paper to a label outlet. In large-scale retail shops, a label printer has to be maintained regularly so as to remove disorders which may adversely affect an operation of repeatedly issuing a large number of labels. The maintenance person replaces the printer parts wasted by the repeated issuance of labels with new ones.
A label printer recently developed employs a static RAM having an area which stores operation history data regarding predetermined operations, such as paper feeding, the driving of motors, and the processing of communication errors. Each time these operations are performed, the operation history data stored in the static RAM are updated. The static RAM is backed up by means of a battery, and retains the operation history data even when the label printer is OFF. The history data can be displayed on a display or printed on label paper under the control of a keyboard, and are used for inspection and repair of the printer. The maintenance person refers to the displayed or printed history data to determine which parts of the printer are wasted or disordered.
If it turns out that a disorder occurs somewhere in the circuit board on which the static RAM is provided, the circuit board is replaced with a spare circuit board so as to prevent completion of the repair from being delayed. As a measure for retaining the operation history data after the replacement, it is thought to display the operation history data on the display and store them in the static RAM provided on the spare circuit board. However, depending upon the kind of the disorder of the circuit board, the operation history data cannot be always displayed on the display. Even if they can be displayed on the display, it is not possible to determine whether the displayed data are correct.
For this reason, the label printer mentioned above is not allowed to retain the operation history data after the replacement of the circuit board. It should be also noted that the operation history data in the static RAM may be lost when the battery voltage falls; in other words, the label printer has problems in that the substantial data storage period is dependent on the charging capacity of the battery.